The present invention concerns microcircuit housing and cable connectors and pertains particularly to a broadband coaxial microwave connector.
For telecommunications applications with signal frequencies below 2 gigahertz, a variety of connectors for coaxial cable systems are used. For example, the most common type of connector is an F-connector that includes a male F-connector part and a female F-connector part. A male F-connector is typically used to terminate a coaxial cable. A female F-connector may be used to join two cables together or to connect a cable to a device.
Other coaxial cable connectors include use of an electrical socket that include cantilever spring tines which terminate in a convex cross section at their free ends. The spring tines expand as they guide an inserted pin during engagement. Another coaxial cable connector uses a circular sleeve having a plurality of spaced-apart, axially oriented tines. Another coaxial cable connector uses spring tabs. For a general discussion on low cost coaxial cable connectors, see for example, U.S. Pat. No. 5,865,654.
For microwave applications, conventional coaxial connectors can include an inner conductor, an outer conductor and an inwardly threaded nut. The inwardly threaded nut is designed to engage an outwardly threaded mating connector. Front faces of respective inner conductors and outer conductors contact each other at a reference plane once the nut is threaded onto the receiving outer conductor. To permit machining of the conductors, a moderately soft conductor material, such as beryllium-copper alloy, is used. To maximize performance, the inner and outer conductors can be gold plated. The gold provides optimal conductivity and resistance to oxidation and other forms of corrosion.
In one microwave coaxial connector, an outer conductor and a coupling nut are configured to incorporate ball bearings therebetween to minimize frictional engagement as the nut is tightened down on a receiving connector. The ball bearings are placed between an outer surface of the outer conductor and an inner surface of the nut. The ball bearings minimize friction between the nut and the outer conductor to which it is coupled. As a result, relative rotation of mating faces is minimized as the nut is tightened. Thus, damage to mating faces is minimized. As an additional advantage, torque-induced stress on cables and devices mechanically coupled to the connectors is minimized. See, for example U.S. Pat. No. 4,801,274.
To achieve a wiping contact on the center conductors, previous connector designs use a pin and slotted socket design. Alternatively, in sexless connectors, compressible collets are imbedded in the ends of the butting center conductors. While this works acceptably for coaxial connectors having a center conductor diameter of about 0.43 millimeter (mm), such connection of center conductors is not practical for a DC to 200 gigahertz (GHz) connector where the center conductor of a transmission line portion has a diameter of about 0.254 mm.
There are connection techniques that can be used for implementing connection of transmission lines where the center conductor of a transmission line has a diameter of about 0.254 mm. These include ribbon bonding or overlapping transmission line connections. However this style of connection is impractical for applications where there are repeated connects and disconnects. Nevertheless, it is desirable to have such a broadband coaxial connector for DC to 200 GHz that can be installed on a test instrument or a microcircuit to be used inside an instrument or a product.
In accordance with the preferred embodiment of the present invention, a connector assembly includes a first connector half and a second. The first connector half includes a first transmission line that has a first outer conductor and a first center conductor. The first center conductor has a first end that has an angled flat region. The second connector half includes a second transmission line. The second transmission line includes a second outer conductor and a second center conductor. The second center conductor has a first end that has an angled flat region. When the first connector half and the second connector half are connected together, the first outer conductor is electrically connected to the second outer conductor. A wiping contact is established between the angled flat region of the first end of the first center conductor and the angled flat region of the first end of the second center conductor.